Gd2O3 hollow nanospheres (HNS) with tuneable size and shell thickness was prepared. The thinnest shell of 30 nm Gd2O3 HNS achieved is 2.9 nm. This ultra-thin Gd2O3 HNS show effective T1 relaxivity in MRI with the highest r1 value of 3.77 mM-1s-1. Furthermore, the Gd2O3 HNS indicate strong chemical and physical stability which will minimize the toxicity caused by released free Gd3+ ions. The monodispersed and tuneable particle size will also facilitate the particle surface modification and blood circulation time design in bio-applications.